Nickel alloy



United States Patent ass'znos ICKE ALLOY -No Drawing.'ApplicationMarch5, 1958 "SerialiNo. 719,204

' 4fClaims. (Cl. 75-123 This inventionrelatestto ferrous alloys andferrous -alloy articles for luse v atyhigh temperatures, referringespecially to alloy articles-suitable for use in applications wherehighstrength at, elevated temperatures is required.

Thetrend inmodern engineering is towards the utili- ;Zation ,of hightemperatures for many and diverse'opera- -tions. As anexample,chemicalprocesses are conducted .todayat high temperatures, anotable instance being in the field of petroleum refining. Alloys withhigh strength :at elevated temperatures are also required as furnaceparts-in the form of supportsand channelsiof one kind ;or anotherinwhich processes are operated at high temperatures. Such furnaces, maycontain'tubes, either cast orwrought, ortrolls that act as conveyorsforparts moving-through the furnaces, or they may contain metal trays:that-are constantly being brought in and out of thefurnacewithfrequentheating.andcooling resulting in drastic-changes intemperatures. .In some instances, ends a :of metaltubes, usuallyreferred to in the art as reactor .tubes, areoperatedin such fashionthat one end is hot and theother is cool. In this case the necessity forhaving available metal-that will Withstand temperature vari- "ationsaswell :as rapidchangesin temperature is a requirement that is diificultto meet.

The aforementioned furnaces and furnace parts that havebeen usedsuccessfully in commercial processes in :the past have'been producedfrom alloys that-contain in addition to chromiu'msubstantial proportionsof nickel. tlnvariably, these alloys have contained anywhere from:about.30%ito 60% nickel. It is awell known fact that in recent yearsthe industrialdemands for nickelhave been at least equal to, and-in somecases in excess of, availability.

' Thisstate 'of afiairs has created anunfavorablecon- *dit'ion inregard-to-the economic use of alloys at the high temperatures.Ithasbrought stress on the users of highinickel content alloys -to .suchan extent that substitutes .have'been tried with resultingunsatisfactory service and increased cost in operation. The supplyofnickel has .notincreased'to such -an.extent that it is a-free commodity,andxcontinued hardship will confront.both the producers and users of thehigh-nickel-content alloys. in .orderto obtain materials of constructionthat are .eco- :nomically suited, for high :temperature applications.

Other applications ,in'which high-nickel alloysv are. used are;insuchdevices assuperchargers, gasturbines; jet propulsionaapparatus;and thelike, land it is necessary in these uinstances.forithepmaterials towithstand deterioration at :high temperatures and under high:rnechanical stress vwithtout failure due to --:excess 1 defamation or:cracking.

Usually the temperatures involved in all suchtypesof applications are inexcess of 1200 F., and in many 1nstances the temperatures :generallyexceed 1500 F. Typical of the compositions that have been used in suchapplications are alloys containing from 15% to 20% of chromium and from35% to 60% of nickel, the remainder being iron with minor percentages ofother constituents such as carbon, manganese, silicon and impuritiessuch as phosphorous and sulphur.

2,892,703 Patented .June 30, 19 59 ICC . 2 The'principal object of thisinvention is to provide new ferrous alloys which contain much less thanabout 30% of nickel and which will successfully resist oxidation and'will withstandhigh applied stresses at temperatures of 5 from aboutl200 to somewhat in excess of about This object is attainedby.the.present. invention which provides alloys of new compositions andproperties. The

principal ingredients of the alloys of this invention are carbon,chromium, nickel, manganese,.nitrogen and columbium withadequatepercentages of silicon for quality purposes, and incidentalimpurities, such as phosphorous and sulphur.

Itisimportant thatcertain of these elements should be present in theproper proportions and percentages.

The nickel should not be less than about 15% nor more than about and thecombined chromium and nickel I content should range between about 25%and about 50%,

and the manganese should range between about 5% and 20 about 15%. "Whencolumbium and nitrogen are present in certain percentages in alloyscontaining those percentages of cl1romium,-nickel and manganese, thealloys will have high temperaturestrength quite comparable with that ofprior highchrome, high nickel alloys containing 5 from 35% to'60% ofnickel. And even When the nickel content is as low as 10% or 15%, thepresent alloywill have high'temperaturestrength heretofore thought to beimpossible to] attain inalloys of that low nickel content.

This new and unexpectedhigh temperature strength-is traceable in largepart to' the presence of the three elements, high manganese, columbiumand nitrogen, as'is indicated by the fact'that When either columbium ornitrog'en is omittedfthe high temperature strength is great ly reduced.

Inalloys of the foregoing composition it is to be under stood that theremainder of the composition is iron with usual impurity amounts ofsulphur and phosphorous, medium carbon, and moderate amounts of silicon.

This, invention'is also embodied in alloys having the 4 followingintermediate composition range within the foregoing broad range:

Carbon From about 30% to about .50%.

Chromium From about 15% to 25% maximum. Nickel From about 10% to about25%.

.Manganese From about 5% to about 15 "Silicon From about .9% to about1.5%.

Nitrogen From about .05 to about .5 Columbium From about .75 to about1.5%.

the remainder being iron with not more than about .05

.ofeach of phosphorous and sulphur.

A-narrower andpreferred range of ingredients is as follows:

Carbon From about .30%to about 50%.

' Chromium From about 19% to about-22%. Nickel From about 19% to about22%. "Manganese From about 8% to about 11%.

Silicon From about .9% to about 1.5

Nitrogen From about .05% to about .5

Columbium From about .75 to about 1.5%.

i .theremainder being iron with not more than about 04% of each ofphosphorous and sulphur.

Apreferred alloy:has.the :following composition:

with the remainder being iron with not more than about .025 ofphosphorous and not more than about .022% of sulphur.

Physical properties of the preferred composition are shown 1n thefollowing table:

Short Time High Temperature Properties:

Tensile Strength (p.s i) 54, 100 30, 600 Elongation in 2 11. 5 14. 0Reduction in Area 10. 4 37. 8 Room Temperature Physical Properties:

Yield Point (p.s.i.) 53,250 Tensile Strength (p.s.i.).. 83, 750Elongation in 2. ll. 0 Reduction in Area" 12. 6

Stressrupture at 1,600 F. and 7,000 p.s.i. load: Time in Hours toRupture 1,103 Hrs. Air Oxidation Resistance at 1,800 F .0097696 inch peryear.

more resistant to air oxidation, than alloys which have been usedextensively heretofore to resist high temperatures and which contained amuch higher nickel content. Since it was generally believed that a highnickel content was required to confer high heat resisting properties onthe alloy, it is a surprising and unobvious discovery that even betterproperties at high temperatures can be obtained by this invention wtihgreatly reduced amounts of nickel.

It is to be understood that many different alloys may be made within thelimits of the foregoing broad composition ranges and that each suchalloy will embody the present invention and will, at least to anappreciable extent, possess the above-stated properties.

All of the test results described in the foregoing tables have beenobtained on cast samples, but it should be pointed out that this in noway limits the invention as all of these alloys are capable of being hotworked into various and sundry items such as billetspforgings, bars,sheet, and strip. It should be understood that when it is necessary toproduce such items-for fabrication into equipment serving attemperatures of about 1200 F., this practice is also included and formsa .part of the invention.

Alloys embodying the present invention may be made either from virginmetal or scrap metal. A convenient way to make these alloys is to selectscrap metal of the chrome-nickel types and to proportion such scrap in amanner to obtain the above-specified chrome-nickel contents. Since thechrome-nickel scrap contains iron and iron contains such elements as.carbon and impurity amounts of phosphorous and sulphur, the desiredamounts of iron and such elements may be provided by proportioning thechrome-nickel scrap oradding iron or iron containing alloys[ Themanganese may be in the form of term-manganese. The nitrogen may beconveniently added in the form of high nickel bearing term-chrome alloy.All these metals may be melted down at the same time.

Having thus described this invention in such full, clear, concise andexact terms as to enable any person skilled in the art to which itpertains to make and use the same,

and having set forth the best mode contemplated of carrying out thisinvention, we state that the subject-matter which we regard as being ourinvention is particularly pointed out and distinctly claimed in what isclaimed, it being understood that equivalents or modifications of, orsubstitutions for, parts of the above specifically described embodimentsof the invention may be made without departing from the scope of theinvention as set forth in what is claimed.

What is claimed is:

1. A nickel chrome iron alloy having a tensile strength above about50,000 pounds per square inch at 1400 R, an air oxygen resistance ofless than about .010 inch per year at 1800 F., and a resistance torupture for about 1100 hours under a stress of about 7000 pounds persquare inch applied at about 1600 F. and consisting essentially of notless than about 10% or more than about 25%, of nickel sufiicientchromium not exceeding about 25% to bring the combined nickel andchromium content to between about 25% and about 50%, between about 5%and about 15% of manganese, between about .75 and about 1.5% ofcolumbium, between about .05% and about .5% of nitrogen, the remainderbeing moderate amounts of silicon and iron containing medium carbon andusual impurity amounts of sulphur and phosphorous.

2. A nickel chrome iron alloy having a tensile strength above about50,000 pounds per square inch at 1400 R, an air oxygen resistance ofless than about .010 inch per year at 1800 F., and a resistance torupture for about 1100 hours under a stress of about 7000 pounds persquare inch applied at about 1600 F. and consisting essentially ofbetween about 30% and about 5 of carbon, between about 15% and about 25%of chromium, between about 10% and about 25% of nickel, between about 5%and about 15% of manganese, between about .9% and about 1.5 of silicon,between about .75% and about 1.5 of columbium, and between about .05%and about .5% of nitrogen, the remainder being iron with not more thanabout .05 of each of sulphur and phosphorous.

3. A nickel chrome iron alloy having a tensile strength above about50,000 pounds per square inch at 1400 R, an air oxygen resistance ofless than about .010 inch per year at 1800 F., and a resistance torupture for about 1100 hours under a stress of about 7000 pounds persquare inch applied at about 1600 F. and consisting essentiallyofbetween about 30% and about .50% of carbon, between about 19% and about22% of chromium, between about 19% and about 22% of nickel, betweenabout 8% and about 11% of manganese, between about .9% and about 1.5% ofsilicon, between about .75% and about 1.5 of columbium, and betweenabout .05 and about .75% of nitrogen, the remainder being iron with notmore than about .04% of each of sulphur and phosphorous.

4. A nickel chrome iron alloy having a tensile strength above about50,000 pounds per square inch at 1400 R, an air oxygen resistance ofless than about .010 inch per year at 1800 F., and a resistance torupture for about 1100 hours under a stress of about 7000 pounds persquare inch applied at about 1600 F. and consisting essentially of .38%of carbon, about 21.4% of chromium, about 20.6% of nickel, about 9.3% ofmanganese, about .94% of silicon, about 1.02% of columbium, and about20% of nitrogen, the remainder being iron with not more than about .04%of each of sulphur and phosphorous.

No references cited.

1. A NICKEL CHROME IRON ALLOY HAVING A TENSILE STRENGTH ABOVE ABOUT50,000 POUNDS PER SQUARE INCH AT 1400* F., AN AIR OXYGEN RESISTANCE OFLESS THAN ABOUT 0.10 INCH PER YEAR AT 1800* F. AND A RESISTANCE TORUPTURE FOR ABOUT 1100 HOURS UNDER A STRESS OF ABOUT 7000 POUNDS PERSQUARE INCH APPLIED AT ABOUT 1600* F. AND CONSISTING ESSENTIALLY OF NOTLESS THAN ABOUT 10% OR MORE THAN ABOUT 25%, OF NICKEL SUFFICIENTCHROMIUM NOT EXCEEDING ABOUT 25% TO BRING THE COMBINED NICKEL ANDCHROMIUM CONTENT TO BETWEEN ABOUT 25% AND ABOUT 50%, BETWEEN ABOUT 5%AND ABOUT 15% OF MANGESE, BETWEEN ABOUT .75% AND ABOUT 1.5% OFCOLUMBIUM, BETWEEN ABOUT .05% AND ABOUT .5% OF NITROGEN, THE REMAINDERBEING MODERATE AMOUNTS OF SILICON AND IRON CONTAINING MEDIUM CARBON ANDUSUAL IMPURITY AMOUNTS OF SULPHUR AND PHOSPHOROUS.